Dungeons and Dragons

word of advice from a seasoned veteran DM: paying attention to components is a great way to keep your spell casters more in line with the martial characters when it comes to utility and combat (otherwise, they'll eventually end up stealing the show).

For instance, Revivify is a great spell - 3rd level, relatively common on spell lists, and is a great way to keep PCs alive in the early-to-mid game. But, without component requirements, it can very easily turn into a crutch for a party, where a Paladin or Barbarian will make their heroic stand every battle, simply because they know the cleric/paladin/druid/artificer/etc. has a "get out of death free" card up their sleeve.

Unless, of course, you require the 300 gp of diamonds for each use of the spell. Sure, by the time the character can cast 3rd level spells, 300 gp is relatively inexpensive. But, the specific requirement of diamonds adds in a layer of sourcing. Maybe they could only find 600 gp of diamonds in their last large city they passed through, and so now they've only got two Revivify spells to last them? Suddenly, that "get out of death free" card turns into a valuable resource the party has to manage. Or that small amount of diamonds they were given as a reward becomes far more valuable.

Even better is Banishment - which requires "something distasteful to the target".

In mid-to-late game, this becomes even more prominent, with spells like "Circle of Death" requiring 500 gp worth of rare components, or Holy Aura (super powerful divine spell that gives nearby party members advantage on all saving throws, and enemies disadvantage on all attack roles against them) requiring a religious reliquary from either a saint or holy book that's worth at lease 1000 gp.

You don't necessarily want to restrict/punish what they can do, but you don't want to give them a completely blank check either.